Planetary transmissions having three non-continuously interconnected gear sets

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least eight forward speed ratios and one reverse speed ratio. The transmission family members include three planetary gear sets having seven torque-transmitting mechanisms. None of the members of the planetary gear sets are continuously grounded or continuously connected with any other member of the planetary gear sets. The powertrain includes an engine and torque converter that is continuously connected to at least one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The seven torque-transmitting mechanisms provide interconnections between various gear members and the transmission housing, and are operated in combinations of five to establish at least eight forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a family of power transmissions havingthree planetary gear sets that are controlled by seventorque-transmitting devices to provide at least eight forward speedratios and at least one reverse speed ratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times. The number of forward speed ratios that are availablein the transmission determines the number of times the engine torquerange is repeated. Early automatic transmissions had two speed ranges.This severely limited the overall speed range of the vehicle andtherefore required a relatively large engine that could produce a widespeed and torque range. This resulted in the engine operating at aspecific fuel consumption point during cruising, other than the mostefficient point. Therefore, manually-shifted (countershafttransmissions) were the most popular.

With the advent of three- and four-speed automatic transmissions, theautomatic shifting (planetary gear) transmission increased in popularitywith the motoring public. These transmissions improved the operatingperformance and fuel economy of the vehicle. The increased number ofspeed ratios reduces the step size between ratios and therefore improvesthe shift quality of the transmission by making the ratio interchangessubstantially imperceptible to the operator under normal vehicleacceleration.

It has been suggested that the number of forward speed ratios beincreased to six or more. Six-speed transmissions are disclosed in U.S.Pat. No. 4,070,927 issued to Polak on Jan. 31, 1978; and U.S. Pat. No.6,422,969 issued to Raghavan and Usoro on Jul. 23, 2002.

Six-speed transmissions offer several advantages over four- andfive-speed transmissions, including improved vehicle acceleration andimproved fuel economy. While many trucks employ power transmissionshaving six or more forward speed ratios, passenger cars are stillmanufactured with three- and four-speed automatic transmissions andrelatively few five or six-speed devices due to the size and complexityof these transmissions.

Seven-speed transmissions are disclosed in U.S. Pat. No. 6,623,397issued to Raghavan, Bucknor and Usoro. Eight speed transmissions aredisclosed in U.S. Pat. No. 6,425,841 issued to Haka. The Hakatransmission utilizes three planetary gear sets and six torquetransmitting devices, including two brakes and two clutches, to provideeight forward speed ratios and a reverse speed ratio. One of theplanetary gear sets is positioned and operated to establish two fixedspeed input members for the remaining two planetary gear sets. Seven-,eight- and nine-speed transmissions provide further improvements inacceleration and fuel economy over six-speed transmissions. However,like the six-speed transmissions discussed above, the development ofseven-, eight- and nine-speed transmissions has been precluded becauseof complexity, size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved familyof transmissions having three planetary gear sets controlled to provideat least eight forward speed ratios and at least one reverse speedratio.

In one aspect of the present invention, the family of transmissions hasthree planetary gear sets, each of which includes a first, second andthird member, which members may comprise a sun gear, a ring gear, or aplanet carrier assembly member.

In referring to the first, second and third gear sets in thisdescription and in the claims, these sets may be counted “first” to“third” in any order in the drawings (i.e., left to right, right toleft, etc.).

In another aspect of the present invention, each of the planetary gearsets may be of the single pinion-type or of the double pinion-type.

In yet another aspect of the present invention, members of each of theplanetary gear sets are not continuously interconnected with members ofother planetary gear sets.

In yet a further aspect of the invention, each family memberincorporates an input shaft which is continuously connected with amember of the planetary gear sets, and an output shaft which iscontinuously connected with another member of the planetary gear sets.

In still a further aspect of the invention, a first torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst planetary gear set with a member of the second planetary gear set.

In another aspect of the invention, a second torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thesecond planetary gear set with a member of the third planetary gear set.

In a still further aspect of the invention, a third torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thethird planetary gear set with a member of the first planetary gear set.

In a still further aspect of the invention, a fourth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst planetary gear set with a member of the second or third planetarygear set.

In a still further aspect of the invention, a fifth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set.

In still another aspect of the invention, a sixth torque-transmittingmechanism, such as a brake, selectively connects a member of the first,second or third planetary gear set with the stationary member(transmission case).

In still another aspect of the invention, a seventh torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set. Alternatively, the seventhtorque-transmitting mechanism, such as a brake, selectively connects amember of the first, second or third planetary gear set with thestationary member (transmission case).

In still another aspect of the invention, the seven torque-transmittingmechanisms are selectively engageable in combinations of five to yieldat least eight forward speed ratios and at least one reverse speedratio.

The above objects and other objects, features, and advantages of thepresent invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

FIG. 1 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1 a;

FIG. 2 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 2 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2 a;

FIG. 3 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 3 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3 a;

FIG. 4 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 4 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4 a;

FIG. 5 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 5 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5 a;

FIG. 6 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 6 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6 a;

FIG. 7 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 7 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7 a;

FIG. 8 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 8 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8 a;

FIG. 9 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 9 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9 a;

FIG. 10 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

FIG. 10 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 10 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like characters represent the same orcorresponding parts throughout the several views, there is shown in FIG.1 a a powertrain 10 having a conventional engine and torque converter12, a planetary transmission 14, and a conventional final drivemechanism 16.

The planetary transmission 14 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 18, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 18 includesthree planetary gear sets 20, 30 and 40.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly 26. The planet carrier assembly26 includes a plurality of pinion gears 27 rotatably mounted on acarrier member 29 and disposed in meshing relationship with both the sungear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the sun gear member 32 and the ring gear member 34.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47 rotatablymounted on a carrier member 49 and disposed in meshing relationship withboth the sun gear member 42 and the ring gear member 44.

The planetary gear arrangement also includes seven torque-transmittingmechanisms 50, 52, 54, 56, 57, 58 and 59. The torque-transmittingmechanisms 50, 52, 54, 56, 57 and 58 are rotating-typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 59 is a stationary-type torquetransmitting mechanism, commonly termed brake or reaction clutch.

The input shaft 17 is continuously connected with ring gear member 24.The output shaft 19 is continuously connected with the ring gear member44.

The clutch 50 selectively connects the planet carrier assembly member 26with the sun gear member 32. The clutch 52 selectively connects the sungear member 22 with the sun gear member 32. The clutch 54 selectivelyconnects the sun gear member 22 with the sun gear member 42. The clutch56 selectively connects the ring gear member 24 with the planet carrierassembly member 46. The clutch 57 selectively connects the planetcarrier assembly member 36 with the sun gear member 42. The clutch 58selectively connects the planet carrier assembly member 36 with theplanet carrier assembly member 46. The brake 59 selectively connects thering gear member 34 with the transmission housing 60.

As shown in FIG. 1 b, and in particular the truth table disclosedtherein, the torque-transmitting mechanisms are selectively engaged incombinations of five to provide eight forward speed ratios and onereverse speed ratio.

The reverse speed ratio is established with the engagement of theclutches 50, 54, 56, 58 and brake 59. The clutch 50 connects the planetcarrier assembly member 26 with the sun gear member 32. The clutch 54connects the sun gear member 22 with the sun gear member 42. The clutch56 connects the ring gear member 24 with the planet carrier assemblymember 46. The clutch 58 connects the planet carrier assembly member 36with the planet carrier assembly member 46. The brake 59 connects thering gear member 34 with the transmission housing 60. The ring gearmember 24 and planet carrier assembly members 36, 46 rotate at the samespeed as the input shaft 17. The planet carrier assembly member 26rotates at the same speed as the sun gear member 32. The sun gear member22 rotates at the same speed as the sun gear member 42. The speed of theplanet carrier assembly member 26 is determined from the speed of thering gear member 24, the speed of the sun gear member 22, and the ringgear/sun gear tooth ratio of the planetary gear set 20. The ring gearmember 34 does not rotate. The speed of the sun gear member 32 isdetermined from the speed of the planet carrier assembly member 36 andthe ring gear/sun gear tooth ratio of the planetary gear set 30. Thering gear member 44 rotates at the same speed as the output shaft 19.The speed of the ring gear member 44, and therefore the output shaft 19,is determined from the speed of the planet carrier assembly member 46,the speed of the sun gear member 42, and the ring gear/sun gear toothratio of the planetary gear set 40. The numerical value of the reversespeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 20, 30, and 40.

The first forward speed ratio is established with the engagement of theclutches 50, 52, 54, 58 and the brake 59. The clutch 50 connects theplanet carrier assembly member 26 with the sun gear member 32. Theclutch 52 connects the sun gear member 22 with the sun gear member 32.The clutch 54 connects the sun gear member 22 with the sun gear member42. The clutch 56 connects the planet carrier assembly member 36 withthe planet carrier assembly member 46. The brake 59 connects the ringgear member 34 with the transmission housing 60. The planetary gear set20 and sun gear members 32, 42 rotate at the same speed as the inputshaft 17. The planet carrier assembly member 36 rotates at the samespeed as the planet carrier assembly member 46. The ring gear member 34does not rotate. The planet carrier assembly member 36 rotates at aspeed determined from the speed of the sun gear member 32 and the ringgear/sun gear tooth ratio of the planetary gear set 30. The ring gearmember 44 rotates at the same speed as the output shaft 19. The ringgear member 44, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 46, thespeed of the sun gear member 42, and the ring gear/sun gear tooth ratioof the planetary gear set 40. The numerical value of the first forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 30 and 40.

The second forward speed ratio is established with the engagement of theclutches 52, 54, 56, 58 and the brake 59. The clutch 52 connects the sungear member 22 with the sun gear member 32. The clutch 54 connects thesun gear member 22 with the sun gear member 42. The clutch 56 connectsthe ring gear member 24 with the planet carrier assembly member 46. Theclutch 58 connects the planet carrier assembly member 36 with the planetcarrier assembly member 46. The brake 59 connects the ring gear member34 with the transmission housing 60. The ring gear member 24 and planetcarrier assembly members 36, 46 rotate at the same speed as the inputshaft 17. The sun gear members 22, 32 and 42 rotate at the same speed.The ring gear member 34 does not rotate. The speed of the sun gearmember 32 is determined from the speed of the planet carrier assemblymember 36 and the ring gear/sun gear tooth ratio of the planetary gearset 30. The ring gear member 44 rotates at the same speed as the outputshaft 19. The ring gear member 44, and therefore the output shaft 19,rotates at a speed determined from the speed of the planet carrierassembly member 46, the speed of the sun gear member 42, and the ringgear/sun gear tooth ratio of the planetary gear set 40. The numericalvalue of the second forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 30 and 40.

The third forward speed ratio is established with the engagement of theclutches 50, 52, 57, 58 and the brake 59. The clutch 50 connects theplanet carrier assembly member 26 with the sun gear member 32. Theclutch 52 connects the sun gear member 22 with the sun gear member 32.The clutch 57 connects the planet carrier assembly member 36 with thesun gear member 42. The clutch 58 connects the planet carrier assemblymember 36 with the planet carrier assembly member 46. The brake 59connects the ring gear member 34 with the transmission housing 60. Theplanetary gear set 20 and sun gear member 32 rotate at the same speed asthe input shaft 17. The ring gear member 34 does not rotate. The planetcarrier assembly member 36 and planetary gear set 40 rotate at the samespeed as the output shaft 19. The speed of the planet carrier assemblymember 36, and therefore the output shaft 19, is determined from speedof the sun gear member 32 and the ring gear/sun gear tooth ratio of theplanetary gear set 30. The numerical value of the third forward speedratio is determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 30.

The fourth forward speed ratio is established with the engagement of theclutches 52, 56, 57, 58 and the brake 59. The clutch 52 connects the sungear member 22 with the sun gear member 32. The clutch 56 connects thering gear member 24 with the planet carrier assembly member 46. Theclutch 57 connects the planet carrier assembly member 36 with the sungear member 42. The clutch 58 connects the planet carrier assemblymember 36 with the planet carrier assembly member 46. The brake 59connects the ring gear member 34 with the transmission housing 60. Thering gear member 24, planet carrier assembly member 36 and planetarygear set 40 rotate at the same speed as the output shaft 19. The sungear member 22 rotates at the same speed as the sun gear member 32. Thering gear member 34 does not rotate. The speed of the planet carrierassembly member 36, and therefore the output shaft 19, is determinedfrom the speed of the sun gear member 32 and the ring gear/sun geartooth ratio of the planetary gear set 30. The numerical value of thefourth forward speed ratio is determined utilizing the ring gear/sungear tooth ratio of the planetary gear set 30.

The fifth forward speed ratio is established with the engagement of theclutch 50, 52, 56, 57 and 58. In this configuration, the input shaft 17is directly connected to the output shaft 19. The numerical value of thefifth forward speed ratio is 1.

The sixth forward speed ratio is established with the engagement of theclutches 50, 52, 56, 57 and the brake 59. The clutch 50 connects theplanet carrier assembly member 26 with the sun gear member 32. Theclutch 52 connects the sun gear member 22 with the sun gear member 32.The clutch 56 connects the ring gear member 24 with the planet carrierassembly member 46. The clutch 57 connects the planet carrier assemblymember 36 with the sun gear member 42. The brake 59 connects the ringgear member 34 with the transmission housing 60. The planetary gear set20, sun gear member 32, and planet carrier assembly member 46 rotate atthe same speed as the input shaft 17. The ring gear member 34 does notrotate. The planet carrier assembly member 36 rotates at the same speedas the sun gear member 42. The speed of the planet carrier assemblymember 36 is determined from the speed of the sun gear member 32 and thering gear/sun gear tooth ratio of the planetary gear set 30. The ringgear member 44 rotates at the same speed as the output shaft 19. Thering gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member46, the speed of the sun gear member 42, and the ring gear/sun geartooth ratio of the planetary gear set 40. The numerical value of thesixth forward speed ratio is determined utilizing the ring gear/sun geartooth ratios of the planetary gear sets 30 and 40.

The seventh forward speed ratio is established with the engagement ofthe clutches 50, 54, 56, 57 and the brake 59. The clutch 50 connects theplanet carrier assembly member 26 with the sun gear member 32. Theclutch 54 connects the sun gear member 22 with the sun gear member 42.The clutch 56 connects the ring gear member 24 with the planet carrierassembly member 46. The clutch 57 connects the planet carrier assemblymember 36 with the sun gear member 42. The brake 59 connects the ringgear member 34 with the transmission housing 60. The ring gear member 24and planet carrier assembly member 46 rotate at the same speed as theinput shaft 17. The planet carrier assembly member 26 rotates at thesame speed as the sun gear member 32. The sun gear member 22 rotates atthe same speed as the sun gear member 42 and the planet carrier assemblymember 36. The speed of the planet carrier assembly member 26 isdetermined from the speed of the ring gear member 24, the speed of thesun gear member 22, and the ring gear/sun gear tooth ratio of theplanetary gear set 20. The ring gear member 34 does not rotate. Thespeed of the planet carrier assembly member 36 is determined from thespeed of the sun gear member 32 and the ring gear/sun gear tooth ratioof the planetary gear set 30. The ring gear member 44 rotates at thesame speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 46, the speed of the sungear member 42, and the ring gear/sun gear tooth ratio of the planetarygear set 40. The numerical value of the of the seventh forward speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20, 30 and 40.

The eighth forward speed ratio is established with the engagement of theclutches 52, 54, 56, 57 and the brake 59. The clutch 52 connects the sungear member 22 with the sun gear member 32. The clutch 54 connects thesun gear member 22 with the sun gear member 42. The clutch 56 connectsthe ring gear member 24 with the planet carrier assembly member 46. Theclutch 57 connects the planet carrier assembly member 36 with the sungear member 42. The brake 59 connects the ring gear member 34 with thetransmission housing 60. The ring gear member 24 and planet carrierassembly member 46 rotate at the same speed as the input shaft 17. Thesun gear members 22, 42 and planetary gear set 30 do not rotate. Thering gear member 44 rotates at the same speed as the output shaft 19.The ring gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member 46and the ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the eighth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set40.

As set forth above, the engagement schedule for the torque-transmittingmechanisms is shown in the truth table of FIG. 1 b. This truth tablealso provides an example of speed ratios that are available utilizingthe ring gear/sun gear tooth ratios given by way of example in FIG. 1 b.The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 20;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set 30;and the N_(R3)/N_(S3) value is the tooth ratio of the planetary gear set40. Also, the chart of FIG. 1 b describes the ratio steps that areattained utilizing the sample of tooth ratios given. For example, thestep ratio between the first and second forward speed ratios is 1.66,while the step ratio between the reverse and first forward ratio is−0.40.

FIG. 2 a shows a powertrain 110 having a conventional engine and torqueconverter 12, a planetary transmission 114, and a conventional finaldrive mechanism 16.

The planetary transmission 114 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 118, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 118 includesthree planetary gear sets 120, 130 and 140.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly 126. The planet carrierassembly 126 includes a plurality of pinion gears 127 rotatably mountedon a carrier member 129 and disposed in meshing relationship with boththe sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of pinion gears 137 rotatablymounted on a carrier member 139 and disposed in meshing relationshipwith both the sun gear member 132 and the ring gear member 134.

The planetary gear set 140 includes a sun gear member 142, a ring gearmember 144, and a planet carrier assembly member 146. The planet carrierassembly member 146 includes a plurality of pinion gears 147 rotatablymounted on a carrier member 149 and disposed in meshing relationshipwith both the sun gear member 142 and the ring gear member 144.

The planetary gear arrangement 118 also includes seventorque-transmitting mechanisms 150, 152, 154, 156, 157, 158 and 159. Thetorque-transmitting mechanisms 150, 152, 154, 156 and 157 arerotating-type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanisms 158 and 159 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the ring gear member124. The output shaft 19 is continuously connected with the planetcarrier assembly member 136.

The planet carrier assembly member 126 is selectively connectable withthe sun gear member 132 through the clutch 150. The planet carrierassembly member 126 is selectively connectable with the planet carrierassembly member 146 through the clutch 152. The sun gear member 122 isselectively connectable with the sun gear member 132 through the clutch154. The sun gear member 122 is selectively connectable with the ringgear member 144 through the clutch 156. The ring gear member 134 isselectively connectable with the ring gear member 144 through the clutch157. The ring gear member 134 is selectively connectable with thetransmission housing 160 through the brake 158. The sun gear member 142is selectively connectable with the transmission housing 160 through thebrake 159.

The truth table of FIG. 2 b describes the engagement sequence utilizedto provide eight forward speed ratios and one reverse speed ratio in theplanetary gear arrangement 118 shown in FIG. 2 a.

The truth tables given in FIGS. 2 b, 3 b, 4 b, 5 b, 6 b, 7 b, 8 b, 9 band 10 b show the engagement sequences for the torque-transmittingmechanisms to provide at least eight forward speed ratios and onereverse ratio. As shown and described above for the configuration inFIG. 1 a, those skilled in the art will understand from the respectivetruth tables how the speed ratios are established through the planetarygear sets identified in the written description.

As set forth above, the truth table of FIG. 2 b describes the engagementsequence of the torque-transmitting mechanisms utilized to provide onereverse drive ratio and eight forward speed ratios. The truth table alsoprovides an example of the ratios that can be attained with the familymembers shown in FIG. 2 a utilizing the sample tooth ratios given inFIG. 2 b. The N_(R1)/N_(S1) value is the tooth ratio of the planetarygear set 120; the N_(R2)/N_(S2) value is the tooth ratio of theplanetary gear set 130; and the N_(R3)/N_(S3) value is the tooth ratioof the planetary gear set 140. Also shown in FIG. 2 b are the ratiosteps between single step ratios in the forward direction as well as thereverse to first ratio step ratio. For example, the first to second stepratio is 1.67.

Turning to FIG. 3 a, a powertrain 210 includes the engine and torqueconverter 12, a planetary transmission 214, and a final drive mechanism16. The planetary transmission 214 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 218, and an output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 218 includes three planetary gear sets 220, 230 and 240.

The planetary gear set 220 includes a sun gear member 222, a ring gearmember 224, and a planet carrier assembly 226. The planet carrierassembly 226 includes a plurality of pinion gears 227 rotatably mountedon a carrier member 229 and disposed in meshing relationship with boththe sun gear member 222 and the ring gear member 224.

The planetary gear set 230 includes a sun gear member 232, a ring gearmember 234, and a planet carrier assembly member 236. The planet carrierassembly member 236 includes a plurality of pinion gears 237 rotatablymounted on a carrier member 239 and disposed in meshing relationshipwith both the sun gear member 232 and the ring gear member 234.

The planetary gear set 240 includes a sun gear member 242, a ring gearmember 244, and a planet carrier assembly member 246. The planet carrierassembly member 246 includes a plurality of pinion gears 247 rotatablymounted on a carrier member 249 and disposed in meshing relationshipwith both the sun gear member 242 and the ring gear member 244.

The planetary gear arrangement 218 also includes seventorque-transmitting mechanisms 250, 252, 254, 256, 257, 258 and 259. Thetorque-transmitting mechanisms 250, 252, 254, 256 and 257 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 258 and 259 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the ring gear member224. The output shaft 19 is continuously connected with the planetcarrier assembly member 236.

The planet carrier assembly member 226 is selectively connectable withthe sun gear member 232 through the clutch 250. The planet carrierassembly member 226 is selectively connectable with the planet carrierassembly member 246 through the clutch 252. The sun gear member 222 isselectively connectable with the sun gear member 232 through the clutch254. The sun gear member 222 is selectively connectable with the ringgear member 244 through the clutch 256. The ring gear member 234 isselectively connectable with the planet carrier assembly member 246through the clutch 257. The ring gear member 234 is selectivelyconnectable with the transmission housing 260 through the brake 258. Thesun gear member 242 is selectively connectable with the transmissionhousing 260 through the brake 259.

As shown in the truth table in FIG. 3 b, the torque-transmittingmechanisms are engaged in combinations of five to establish eightforward speed ratios and one reverse speed ratio.

As previously set forth, the truth table of FIG. 3 b describes thecombinations of engagements utilized for the forward and reverse speedratios. The truth table also provides an example of speed ratios thatare available with the family member described above. These examples ofspeed ratios are determined utilizing the tooth ratios given in FIG. 3b. The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set220; the N_(R2)/N_(S2) value is the tooth ratio of the planetary gearset 230; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 240. Also depicted in FIG. 3 b is a chart representing theratio steps between adjacent forward speed ratios and between the firstand reverse speed ratio. For example, the first to second ratiointerchange has a step of 1.67.

A powertrain 310, shown in FIG. 4 a, includes the engine and torqueconverter 12, a planetary transmission 314, and the final drivemechanism 16. The planetary transmission 314 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 318, and output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 318 includes three planetary gear sets 320, 330 and 340.

The planetary gear set 320 includes a sun gear member 322, a ring gearmember 324, and a planet carrier assembly member 326. The planet carrierassembly member 326 includes a plurality of pinion gears 327 rotatablymounted on a carrier member 329 and disposed in meshing relationshipwith both the sun gear member 322 and the ring gear member 324.

The planetary gear set 330 includes a sun gear member 332, a ring gearmember 334, and a planet carrier assembly member 336. The planet carrierassembly member 336 includes a plurality of pinion gears 337 rotatablymounted on a carrier member 339 and disposed in meshing relationshipwith both the sun gear member 332 and the ring gear member 334.

The planetary gear set 340 includes a sun gear member 342, a ring gearmember 344, and a planet carrier assembly member 346. The planet carrierassembly member 346 includes a plurality of pinion gears 347 rotatablymounted on a carrier member 349 and disposed in meshing relationshipwith both the sun gear member 342 and the ring gear member 344.

The planetary gear arrangement 318 also includes seventorque-transmitting mechanisms 350, 352, 354, 356, 357, 358 and 359. Thetorque-transmitting mechanisms 350, 352, 354, 356 and 357 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 358 and 359 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member322. The output shaft 19 is continuously connected with the planetcarrier assembly member 336.

The ring gear member 324 is selectively connectable with the ring gearmember 344 through the clutch 350. The planet carrier assembly member326 is selectively connectable with the sun gear member 332 through theclutch 352. The planet carrier assembly member 326 is selectivelyconnectable with the planet carrier assembly member 346 through theclutch 354. The ring gear member 334 is selectively connectable with thering gear member 344 through the clutch 356. The ring gear member 334 isselectively connectable with the sun gear member 342 through the clutch357. The ring gear member 324 is selectively connectable with thetransmission housing 360 through the brake 358. The sun gear member 332is selectively connectable with the transmission housing 360 through thebrake 359.

The truth table shown in FIG. 4 b describes the engagement combinationand the engagement sequence necessary to provide one reverse drive ratioand eight forward speed ratios. A sample of the numerical values for theratios is also provided in the truth table of FIG. 4 b. These values aredetermined utilizing the ring gear/sun gear tooth ratios also given inFIG. 4 b. The N_(R1)/N_(S1) value is the tooth ratio for the planetarygear set 320; the N_(R2)/N_(S2) value is the tooth ratio for theplanetary gear set 330; and the N_(R3)/N_(S3) value is the tooth ratiofor the planetary gear set 340. Also given in FIG. 4 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe reverse to first forward speed ratio. For example, the first tosecond forward speed ratio step is 1.51.

A powertrain 410, shown in FIG. 5 a, includes the engine and torqueconverter 12, a planetary transmission 414 and the final drive mechanism16. The planetary transmission 414 includes a planetary gear arrangement418, input shaft 17 and output shaft 19. The planetary gear arrangement418 includes three simple planetary gear sets 420, 430 and 440.

The planetary gear set 420 includes a sun gear member 422, a ring gearmember 424, and a planet carrier assembly 426. The planet carrierassembly 426 includes a plurality of pinion gears 427, 428 rotatablymounted on a carrier member 429 and disposed in meshing relationshipwith the sun gear member 422 and the ring gear member 424, respectively.

The planetary gear set 430 includes a sun gear member 432, a ring gearmember 434, and a planet carrier assembly member 436. The planet carrierassembly member 436 includes a plurality of pinion gears 437 rotatablymounted on a carrier member 439 and disposed in meshing relationshipwith both the ring gear member 434 and the sun gear member 432.

The planetary gear set 440 includes a sun gear member 442, a ring gearmember 444, and a planet carrier assembly member 446. The planet carrierassembly member 446 includes a plurality of pinion gears 447 rotatablymounted on a carrier member 449 and disposed in meshing relationshipwith both the sun gear member 442 and the ring gear member 444.

The planetary gear arrangement 418 also includes seventorque-transmitting mechanisms 450, 452, 454, 456, 457, 458 and 459. Thetorque-transmitting mechanisms 450, 452, 454, 456 and 457 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 458 and 459 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member422. The output shaft 19 is continuously connected with the planetcarrier assembly member 436.

The planet carrier assembly member 426 is selectively connectable withthe ring gear member 444 through the clutch 450. The ring gear member424 is selectively connectable with the sun gear member 432 through theclutch 452. The ring gear member 424 is selectively connectable with theplanet carrier assembly member 446 through the clutch 454. The ring gearmember 434 is selectively connectable with the ring gear member 444through the clutch 456. The ring gear member 434 is selectivelyconnectable with the sun gear member 442 through the clutch 457. Theplanet carrier assembly member 426 is selectively connectable with thetransmission housing through the brake 458. The sun gear member 432 isselectively connectable with the transmission housing 460 through thebrake 459.

The truth table shown in FIG. 5 b describes the engagement combinationand sequence of the torque-transmitting mechanisms 450, 452, 454, 456,457, 458 and 459 that are employed to provide the forward and reversedrive ratios.

Also given in the truth table of FIG. 5 b is a set of numerical valuesthat are attainable with the present invention utilizing the ringgear/sun gear tooth ratios shown. The N_(R1)/N_(S1) value is the toothratio of the planetary gear set 420; the N_(R2)/N_(S2) value is thetooth ratio of the planetary gear set 430; and the N_(R3)/N_(S3) valueis the tooth ratio of the planetary gear set 440.

FIG. 5 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.51.

A powertrain 510, shown in FIG. 6 a, includes an engine and torqueconverter 12, a planetary gear transmission 514 and the final drivemechanism 16. The planetary transmission 514 includes the input shaft17, a planetary gear arrangement 518 and the output shaft 19. Theplanetary gear arrangement 518 includes three planetary gear sets 520,530 and 540.

The planetary gear set 520 includes a sun gear member 522, a ring gearmember 524, and a planet carrier assembly 526. The planet carrierassembly 526 includes a plurality of pinion gears 527 rotatably mountedon a carrier member 529 and disposed in meshing relationship with boththe sun gear member 522 and the ring gear member 524.

The planetary gear set 530 includes a sun gear member 532, a ring gearmember 534, and a planet carrier assembly member 536. The planet carrierassembly member 536 includes a plurality of pinion gears 537 rotatablymounted on a carrier member 539 and disposed in meshing relationshipwith both the sun gear member 532 and the ring gear member 534.

The planetary gear set 540 includes a sun gear member 542, a ring gearmember 544, and a planet carrier assembly member 546. The planet carrierassembly member 546 includes a plurality of pinion gears 547 rotatablymounted on a carrier member 549 and disposed in meshing relationshipwith both the sun gear member 542 and the ring gear member 544.

The planetary gear arrangement 518 also includes seventorque-transmitting mechanisms 550, 552, 554, 556, 557, 558 and 559. Thetorque-transmitting mechanisms 550, 552, 554, 556 and 557 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 558 and 559 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 526. The output shaft 19 is continuously connected withthe planet carrier assembly member 536.

The sun gear member 522 is selectively connectable with the sun gearmember 542 through the clutch 550. The ring gear member 524 isselectively connectable with the ring gear member 534 through the clutch552. The ring gear member 524 is selectively connectable with the planetcarrier assembly member 546 through the clutch 554. The sun gear member532 is selectively connectable with the sun gear member 542 through theclutch 556. The sun gear member 532 is selectively connectable with thering gear member 544 through the clutch 557. The sun gear member 522 isselectively connectable with the transmission housing 560 through thebrake 558. The ring gear member 534 is selectively connectable with thetransmission housing 560 through the brake 559.

The truth table shown in FIG. 6 b describes the engagement sequence andcombination of the torque-transmitting mechanisms to provide the reversespeed ratio and eight forward speed ratios. The chart of FIG. 6 bdescribes the ratio steps between adjacent forward speed ratios and theratio step between the reverse and first forward speed ratio.

The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6 b. TheN_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 520;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set530; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 540.

A powertrain 610, shown in FIG. 7 a, has the engine and torque converter12, a planetary transmission 614 and the final drive mechanism 16. Theplanetary transmission 614 includes the input shaft 17, a planetary geararrangement 618 and the output shaft 19. The planetary gear arrangement618 includes three planetary gear sets 620, 630 and 640.

The planetary gear set 620 includes a sun gear member 622, a ring gearmember 624, and a planet carrier assembly 626. The planet carrierassembly 626 includes a plurality of pinion gears 627 rotatably mountedon a carrier member 629 and disposed in meshing relationship with boththe sun gear member 622 and the ring gear member 624.

The planetary gear set 630 includes a sun gear member 632, a ring gearmember 634, and a planet carrier assembly member 636. The planet carrierassembly member 636 includes a plurality of pinion gears 637 rotatablymounted on a carrier member 639 and disposed in meshing relationshipwith both the sun gear member 632 and the ring gear member 634.

The planetary gear set 640 includes a sun gear member 642, a ring gearmember 644, and a planet carrier assembly member 646. The planet carrierassembly member 646 includes a plurality of pinion gears 647 rotatablymounted on a carrier member 649 and disposed in meshing relationshipwith both the sun gear member 642 and the ring gear member 644.

The planetary gear arrangement 618 also includes seventorque-transmitting mechanisms 650, 652, 654, 656, 657, 658 and 659. Thetorque-transmitting mechanisms 650, 652, 654, 656 and 657 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 658 and 659 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 626. The output shaft 19 is continuously connected withthe planet carrier assembly member 636.

The sun gear member 622 is selectively connectable with the sun gearmember 642 through the clutch 650. The ring gear member 624 isselectively connectable with the ring gear member 634 through the clutch652. The ring gear member 624 is selectively connectable with the planetcarrier assembly member 646 through the clutch 654. The sun gear member632 is selectively connectable with the ring gear member 644 through theclutch 656. The sun gear member 632 is selectively connectable with theplanet carrier assembly member 646 through the clutch 657. The sun gearmember 622 is selectively connectable with the transmission housing 660through the brake 658. The ring gear member 634 is selectivelyconnectable with the transmission housing 660 through the brake 659.

The truth table shown in FIG. 7 b describes the combination oftorque-transmitting mechanism engagements that will provide the reversedrive ratio and eight forward speed ratios, as well as the sequence ofthese engagements and interchanges. The torque-transmitting mechanisms650, 654, 657 and 659 can be engaged through the neutral condition,thereby simplifying the forward/reverse interchange.

The ratio values given are by way of example and are establishedutilizing the ring gear/sun gear tooth ratios given in FIG. 7 b. Forexample, the N_(R1)/N_(S1) value is the tooth ratio of the planetarygear set 620; the N_(R2)/N_(S2) value is the tooth ratio of theplanetary gear set 630; and the N_(R3)/N_(S3) value is the tooth ratioof the planetary gear set 640. The ratio steps between adjacent forwardratios and the reverse to first ratio are also given in FIG. 7 b.

A powertrain 710, shown in FIG. 8 a, has the conventional engine andtorque converter 12, a planetary transmission 714, and the conventionalfinal drive mechanism 16. The engine and torque converter 12 aredrivingly connected with the planetary transmission 714 through theinput shaft 17. The planetary transmission 714 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 714 includes a planetary gear arrangement 718that has a first planetary gear set 720, a second planetary gear set730, and a third planetary gear set 740.

The planetary gear set 720 includes a sun gear member 722, a ring gearmember 724, and a planet carrier assembly 726. The planet carrierassembly 726 includes a plurality of pinion gears 727 rotatably mountedon a carrier member 729. The pinion gears 727 are disposed in meshingrelationship with the sun gear member 722 and the ring gear member 724.

The planetary gear set 730 includes a sun gear member 732, a ring gearmember 734, and a planet carrier assembly member 736. The planet carrierassembly member 736 includes a plurality of pinion gears 737 rotatablymounted on a carrier member 739 and disposed in meshing relationshipwith both the sun gear member 732 and the ring gear member 734.

The planetary gear set 740 includes a sun gear member 742, a ring gearmember 744, and a planet carrier assembly member 746. The planet carrierassembly member 746 includes a plurality of pinion gears 747 rotatablymounted on a carrier member 749 and disposed in meshing relationshipwith both the sun gear member 742 and the ring gear member 744.

The planetary gear arrangement 718 also includes seventorque-transmitting mechanisms 750, 752, 754, 756, 757, 758 and 759. Thetorque-transmitting mechanisms 750, 752, 754, 756 and 757 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 758 and 759 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 726. The output shaft 19 is continuously connected withthe planet carrier assembly member 746.

The sun gear member 722 is selectively connectable with the sun gearmember 742 through the clutch 750. The ring gear member 724 isselectively connectable with the sun gear member 732 through the clutch752. The ring gear member 724 is selectively connectable with the sungear member 742 through the clutch 754. The sun gear member 732 isselectively connectable with the ring gear member 744 through the clutch756. The ring gear member 734 is selectively connectable with the ringgear member 744 through the clutch 757. The sun gear member 722 isselectively connectable with the transmission housing 760 through thebrake 758. The planet carrier assembly member 736 is selectivelyconnectable with the transmission housing 760 through the brake 759.

The truth table of FIG. 8 b defines the torque-transmitting mechanismengagement sequence utilized for each of the forward and reverse speedratios. Also given in the truth table is a set of numerical values thatare attainable with the present invention utilizing the ring gear/sungear tooth ratios given in FIG. 8 b. The N_(R1)/N_(S1) value is thetooth ratio of the planetary gear set 720; the N_(R2)/N_(S2) value isthe tooth ratio of the planetary gear set 730; and the N_(R3)/N_(S3)value is the tooth ratio of the planetary gear set 740.

FIG. 8 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.44.

A powertrain 810, shown in FIG. 9 a, has the conventional engine andtorque converter 12, a planetary transmission 814, and the final drivemechanism 16. The engine and torque converter 12 are drivingly connectedwith the planetary transmission 814 through the input shaft 17. Theplanetary transmission 814 is drivingly connected with the final drivemechanism 16 through the output shaft 19. The planetary transmission 814includes a planetary gear arrangement 818 that has a first planetarygear set 820, a second planetary gear set 830, and a third planetarygear set 840.

The planetary gear set 820 includes a sun gear member 822, a ring gearmember 824, and a planet carrier assembly 826. The planet carrierassembly 826 includes a plurality of pinion gears 827 rotatably mountedon a carrier member 829 and disposed in meshing relationship with thesun gear member 822 and the ring gear member 824.

The planetary gear set 830 includes a sun gear member 832, a ring gearmember 834, and a planet carrier assembly member 836. The planet carrierassembly member 836 includes a plurality of pinion gears 837 rotatablymounted on a carrier member 839 and disposed in meshing relationshipwith both the sun gear member 832 and the ring gear member 834.

The planetary gear set 840 includes a sun gear member 842, a ring gearmember 844, and a planet carrier assembly member 846. The planet carrierassembly member 846 includes a plurality of pinion gears 847 rotatablymounted on a carrier member 849 and disposed in meshing relationshipwith both the ring gear member 844 and the sun gear member 842.

The planetary gear arrangement 818 also includes seventorque-transmitting mechanisms 850, 852, 854, 856, 857, 858 and 859. Thetorque-transmitting mechanisms 850, 852, 854, 856 and 857 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 858 and 859 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member822. The output shaft 19 is continuously connected with the ring gearmember 844.

The sun gear member 822 is selectively connectable with the planetcarrier assembly member 846 through the clutch 850. The planet carrierassembly member 826 is selectively connectable with the planet carrierassembly member 836 through the clutch 852. The planet carrier assemblymember 826 is selectively connectable with the planet carrier assemblymember 846 through the clutch 854. The ring gear member 824 isselectively connectable with the sun gear member 832 through the clutch856. The ring gear member 834 is selectively connectable with the sungear member 842 through the clutch 857. The planet carrier assemblymember 836 is selectively connectable with the transmission housing 860through the brake 858. The sun gear member 832 is selectivelyconnectable with the transmission housing 860 through the brake 859.

The truth table shown in FIG. 9 b defines the torque-transmittingmechanism engagement sequence that provides the reverse speed ratio andeight forward speed ratios shown in the truth table and available withthe planetary gear arrangement 818. A sample of numerical values for theindividual ratios is also given in the truth table of FIG. 9 b. Thesenumerical values have been calculated using the ring gear/sun gear toothratios also given by way of example in FIG. 9 b. The N_(R1)/N_(S1) valueis the tooth ratio of the planetary gear set 820; the N_(R2)/N_(S2)value is the tooth ratio of the planetary gear set 830; and theN_(R3)/N_(S3) value is the tooth ratio of the planetary gear set 840.FIG. 9 b also describes the ratio steps between adjacent forward ratiosand between the reverse and first forward ratio.

The powertrain 910, shown in FIG. 10 a, includes the conventional engineand torque converter 12, a planetary transmission 914, and theconventional final drive mechanism 16. The engine and torque converter12 are drivingly connected with the planetary transmission 914 throughthe input shaft 17. The planetary transmission 914 is drivinglyconnected with the final drive mechanism 16 through the output shaft 19.The planetary transmission 914 includes a planetary gear arrangement 918that has a first planetary gear set 920, a second planetary gear set930, and a third planetary gear set 940.

The planetary gear set 920 includes a sun gear member 922, a ring gearmember 924, and a planet carrier assembly 926. The planet carrierassembly 926 includes a plurality of pinion gears 927 that are rotatablymounted on a carrier member 929 and disposed in meshing relationshipwith the sun gear member 922 and the ring gear member 924, respectively.

The planetary gear set 930 includes a sun gear member 932, a ring gearmember 934, and a planet carrier assembly member 936. The planet carrierassembly member 936 includes a plurality of pinion gears 937 rotatablymounted on a carrier member 939 and disposed in meshing relationshipwith both the sun gear member 932 and the ring gear member 934.

The planetary gear set 940 includes a sun gear member 942, a ring gearmember 944, and a planet carrier assembly member 946. The planet carrierassembly member 946 includes a plurality of pinion gears 947 rotatablymounted on a carrier member 949 and disposed in meshing relationshipwith both the sun gear member 942 and the ring gear member 944.

The planetary gear arrangement 918 also includes seventorque-transmitting mechanisms 950, 952, 954, 956, 957, 958 and 959. Thetorque-transmitting mechanisms 950, 952, 954, 956 and 957 arerotating-type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanisms 958 and 959 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member922. The output shaft 19 is continuously connected with the planetcarrier assembly member 946.

The sun gear member 922 is selectively connectable with the ring gearmember 944 through the clutch 950. The ring gear member 924 isselectively connectable with the planet carrier assembly member 936through the clutch 952. The planet carrier assembly member 926 isselectively connectable with the ring gear member 934 through the clutch954. The planet carrier assembly member 926 is selectively connectablewith the ring gear member 944 through the clutch 956. The sun gearmember 932 is selectively connectable with the sun gear member 942through the clutch 957. The planet carrier assembly member 936 isselectively connectable with the transmission housing 960 through thebrake 958. The ring gear member 934 is selectively connectable with thetransmission housing 960 through the brake 959.

The truth table of FIG. 10 b describes the torque-transmitting mechanismengagement sequence utilized to provide the reverse speed ratio andeight forward speed ratios. The truth table also provides a set ofexamples for the ratios for each of the reverse and forward speedratios. These numerical values have been determined utilizing the ringgear/sun gear tooth ratios given in FIG. 10 b. The N_(R1)/N_(S1) valueis the tooth ratio of the planetary gear set 920; the N_(R2)/N_(S2)value is the tooth ratio of the planetary gear set 930; and theN_(R3)/N_(S3) value is the tooth ratio of the planetary gear set 940.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second and third planetary gear sets each having first,second and third members; said input shaft being continuouslyinterconnected with a member of said planetary gear sets, and saidoutput shaft being continuously interconnected with another member ofsaid planetary gear sets; wherein none of said members of said planetarygear sets are continuously grounded or continuously connected with anyother member of said planetary gear sets; a first torque-transmittingmechanism selectively interconnecting a member of said first planetarygear set with a member of said second planetary gear set; a secondtorque-transmitting mechanism selectively interconnecting a member ofsaid second planetary gear set with a member of said third planetarygear set; a third torque-transmitting mechanism selectivelyinterconnecting a member of said third planetary gear set with a memberof said first planetary gear set; a fourth torque-transmitting mechanismselectively interconnecting a member of said first planetary gear setwith a member of said second or third planetary gear set; a fifthtorque-transmitting mechanism selectively interconnecting a member ofsaid first, second or third planetary gear set with another member ofsaid first, second or third planetary gear set; a sixthtorque-transmitting mechanism selectively interconnecting a member ofsaid first, second or third planetary gear set with a stationary member;a seventh torque-transmitting mechanism selectively interconnecting amember of said first, second or third planetary gear set with anothermember of said first, second or third planetary gear set, or with saidstationary member; said torque-transmitting mechanisms being engaged incombinations of five to establish at least eight forward speed ratiosand at least one reverse speed ratio between said input shaft and saidoutput shaft.
 2. The transmission defined in claim 1, wherein saidfirst, second, third, fourth, fifth and seventh torque-transmittingmechanisms comprise clutches, and said sixth torque-transmittingmechanism comprises a brake.
 3. The transmission defined in claim 1,wherein said first, second, third, fourth and fifth torque-transmittingmechanisms comprise clutches, and said sixth and seventhtorque-transmitting mechanisms comprises brakes.
 4. The transmissiondefined in claim 1, wherein planet carrier assembly members of each ofsaid planetary gear sets are single-pinion carriers.
 5. The transmissiondefined in claim 1, wherein at least one planet carrier assembly memberof said planetary gear sets is a double-pinion carrier.
 6. A multi-speedtransmission comprising: an input shaft; an output shaft; a planetarygear arrangement having first, second and third planetary gear sets,each planetary gear set having first, second and third members; saidinput shaft being continuously interconnected with a member of saidplanetary gear sets, and said output shaft being continuouslyinterconnected with another member of said planetary gear sets; whereinnone of said members of said planetary gear sets are continuouslygrounded or continuously connected with any other member of saidplanetary gear sets; and seven torque-transmitting mechanisms forselectively interconnecting said members of said planetary gear setswith a stationary member or with other members of said planetary gearsets, said seven torque-transmitting mechanisms being engaged incombinations of five to establish at least eight forward speed ratiosand at least one reverse speed ratio between said input shaft and saidoutput shaft.
 7. The transmission defined in claim 6, wherein a first ofsaid seven torque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said first planetary gear set with a memberof said second planetary gear set.
 8. The transmission defined in claim6, wherein a second of said seven torque-transmitting mechanisms isoperable for selectively interconnecting a member of said secondplanetary gear set with a member of said third planetary gear set. 9.The transmission defined in claim 6, wherein a third of said seventorque-transmitting mechanisms is selectively operable forinterconnecting a member of said third planetary gear set with a memberof said first planetary gear set.
 10. The transmission defined in claim6, wherein a fourth of said seven torque-transmitting mechanisms isselectively operable for interconnecting a member of said firstplanetary gear set with a member of said second or third planetary gearset.
 11. The transmission defined in claim 6, wherein a fifth of saidseven torque-transmitting mechanisms is selectively operable forinterconnecting a member of said first, second or third planetary gearset with another member of said first, second or third planetary gearset.
 12. The transmission defined in claim 6, wherein a sixth of saidseven torque-transmitting mechanisms selectively interconnects a memberof said first, second or third planetary gear set with said stationarymember.
 13. The transmission defined in claim 6, wherein a seventh ofsaid seven torque-transmitting mechanisms selectively interconnects amember of said first or third planetary gear set with another member ofsaid first, second or third planetary gear set, or with said stationarymember.
 14. The transmission defined in claim 6, wherein planet carrierassembly members of each of said planetary gear sets are single-pinioncarriers.
 15. The transmission defined in claim 6, wherein at least oneplanet carrier assembly member of said planetary gear sets is adouble-pinion carrier.